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post #1 of 6 Old 08-17-2009, 06:40 AM Thread Starter
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4.0 Performance upgrades.

Is there any good aftermarket engine upgrades that will give my 04 4.0L a little more power without going into any major internal work?

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post #2 of 6 Old 08-17-2009, 07:00 AM
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Short answer = No.

Long answer = No, there isn't.

Longer answer = There are a lot of things advertised to give better MPG and more HP. Some will give higher HP but you get it at the high end of the RPM range which doesn't do a lot of good for a Jeep. Most of the people will tell you these things are a waste of money. Some will claim that they "feel" more power with X but it's mostly just "feeling" lighter in the wallet that they are feeling and maybe a different sound from the intake.

Best answer = Since you are running 30" tires, stroke it. Nothing makes power better than displacement. If you go with bigger tires, regear.

Keep in mind that free advice can frequently be worth less than you pay for it.
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post #3 of 6 Old 08-17-2009, 10:46 AM Thread Starter
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Hey,thanks for that info. im glad i asked first. is there somwhere you can direct me so i can do some research on stroking a 4.0?
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post #4 of 6 Old 08-17-2009, 11:08 AM
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post #5 of 6 Old 08-17-2009, 11:28 AM
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Originally Posted by boondaba View Post
Is there any good aftermarket engine upgrades that will give my 04 4.0L a little more power without going into any major internal work?
nope. stroker, supercharger, turbo or don't even bother opening your wallet. in case you were wondering about Cold Air Intakes - read here: http://www.jeepforum.com/forum/f9/faq-cold-air-intake-558437/
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post #6 of 6 Old 08-17-2009, 11:49 AM
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The correct answer here is YES.

However, this really depends on your definition of MAJOR internal work. Stroking an engine properly is about as major as it gets. Its going to include a lot of refinishing, and balancing. Ive been building engines on and off for a little over 16yrs, and almost all your power increases are going to be found in the head, and the camshaft. If you're willing to spend money on machine work, then spend it on the head... forget the bottom end. The phrase, "Nothing makes power better than displacement." can be very true, as long as the supporting modifications are applied. A good port and polish can yield and an aggressive camshaft will yield far more horsepower than any stroke. Funny story, when I looked up all the tried and trued stroker engines, I was really astonished that the most aggressive combination only yielded 303hp & 360lb-ft.... A BMW M3 can make that all day with 3.0L, and it has room to play with all the way to 400hp on the motor... the difference is, head flow, and Camshafts. That's the route to explore. Now if your only interested in finding raw torque, then a you have to lay hard ball and do the stroke, and complete it with the proper head work and camshaft.

Let me explain something... when an engine has a handicap, the last thing you want to do is make it worse. The RPM range is short for two reasons: 1. The stroke, and 2. The cam grind. By just stroking the engine all you've really done is added more weight and more displacement, but the engine still has the same handicap except now its worse. To really open up the possibilities, honestly, it should be De-stroked... but i don't believe that there is such a crankshaft available. Going in that direction is also very expensive, and very tricky w/o the proper know how, so a small block Chevy would be the better route.
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